Palai Giacomo, Caruso Giovanni, Gucci Riccardo, D'Onofrio Claudio
Department of Agriculture Food and Environment, University of Pisa, Pisa, Italy.
Front Plant Sci. 2023 Feb 20;14:1117572. doi: 10.3389/fpls.2023.1117572. eCollection 2023.
The impact of water deficit on volatile organic compounds (VOCs) responsible for grape aroma remains quite unclear. The aim of this study was to evaluate the effect of different timing and intensity of water deficit on berry VOCs and on their biosynthetic pathways. Fully irrigated control vines were compared with the following treatments: i) two different levels of water deficit from berry pea-size through veraison, ii) one level of water deficit during the lag-phase, and iii) two different levels of water deficit from veraison through harvest. At harvest, total VOC concentrations were higher in berries of water stressed vines from berry pea size through veraison or during the lag phase, whereas post-veraison water deficit determined similar concentrations as control. This pattern was even more pronounced for the glycosylated fraction and was also observed for single compounds, mainly monoterpenes and C-norisoprenoids. On the other hand, free VOCs were higher in berries from lag phase or post-veraison stressed vines. The significant glycosylated and free VOCs increment measured after the short water stress limited to the lag phase highlight the pivotal role played by this stage in berry aroma compound biosynthesis modulation. The severity of water stress before veraison was also important, since glycosylated VOCs showed a positive correlation with the pre-veraison daily water stress integral. The RNA-seq analysis showed a wide regulation induced by irrigation regimes on terpenes and carotenoids biosynthetic pathways. The terpene synthases and glycosyltransferases as well as genes of the network of transcription factors were upregulated, especially in berries from pre-veraison stressed vines. Since the timing and intensity of water deficit contribute to regulate berry VOCs, irrigation management can be used to achieve high-quality grapes while saving water.
水分亏缺对葡萄香气挥发性有机化合物（VOCs）的影响仍相当不清楚。本研究的目的是评估不同时间和强度的水分亏缺对浆果VOCs及其生物合成途径的影响。将充分灌溉的对照葡萄藤与以下处理进行比较：i）从浆果豌豆大小到转色期的两种不同程度的水分亏缺，ii）滞育期的一种水分亏缺水平，以及iii）从转色期到收获期的两种不同程度的水分亏缺。收获时，从浆果豌豆大小到转色期或滞育期水分胁迫的葡萄藤浆果中总VOC浓度较高，而转色期后的水分亏缺导致的浓度与对照相似。这种模式在糖基化部分更为明显，在单一化合物中也观察到，主要是单萜和C-去甲类异戊二烯。另一方面，滞育期或转色期后受胁迫葡萄藤的浆果中游离VOCs含量较高。在仅限于滞育期的短期水分胁迫后测得的糖基化和游离VOCs的显著增加突出了该阶段在浆果香气化合物生物合成调节中所起的关键作用。转色期前水分胁迫的严重程度也很重要，因为糖基化VOCs与转色期前每日水分胁迫积分呈正相关。RNA测序分析表明，灌溉制度对萜类和类胡萝卜素生物合成途径有广泛的调控作用。萜类合酶和糖基转移酶以及转录因子网络的基因被上调，特别是在转色期前受胁迫葡萄藤的浆果中。由于水分亏缺的时间和强度有助于调节浆果VOCs，因此灌溉管理可用于在节水的同时实现葡萄的高品质。
